The present invention relates generally to the construction of a steam trap operative to discharge condensate, and more particularly, to a steam trap having a valve which is opened and closed by the bending action of a stack of bimetallic plates occurring as a result of temperature variation.
Bimetallic valve control elements normally involve a pair of metallic plates having different coefficients of thermal expansion which will bend as a result of variation in temperatures. Such bimetallic control plates may exhibit disadvantages due to slow rates of bending variation and low sensitivity to temperature change. Furthermore, bimetallic control devices may be difficult to support within a steam trap inasmuch as large external forces may cause damage thereto.
In conventional valve controls, a plurality of bimetallic plates may be arranged in such a manner that the variation in bending of all of the plates may be cumulatively applied in order to supplement a smaller or slower rate of bending variation in each of the individual bimetallic plates. In such an assembly, larger external forces involved in controlling the opening and closing of a valve may be better supported.
Nevertheless, in such bimetallic valve control devices utilizing plural discs of bimetallic plates stacked in layers, it is still difficult to avoid problems because of the fact that such control members are subjected to forces arising upon opening and closing of a valve member and also fluid pressure forces acting thereon as well as other elastic forces.
Thus, bimetallic control devices are always subjected to large external forces and, additionally, are exposed to ambient fluid pressures and temperatures which are rather high and which may adversely effect performance of the control. Therefore, the performance of bimetallic control devices may easily change and deteriorate because of electro-chemical erosion of the parts or because of cracking due to stress. Thus, the problem arises in that the steam trap involving bimetallic valve controls may not exhibit a uniform performance characteristic over an extended period of time but may require frequent adjustment. Furthermore, the operative life of such steam traps may be significantly shortened due to malfunction of the bimetallic valve controls.
The present invention is intended to overcome the aforementioned disadvantages of steam traps having bimetallic valve controls and to provide a bimetallically controlled steam trap which operates to apply larger forces to open and close the valve of the steam trap, thereby providing firmer more secure valve operation. Additionally, the present invention aims for providing bimetallic valve control means having superior durability and more uniform operating performance over a longer period of time. Additionally, with the arrangement of the present invention, a greater reliability in operation may be achieved.